P3424WE, custom PBP resolutions?

I recently got the Dell P3424WE 34" and want to connect two displays, with one side a standard 16:9 (2560 x 1440) and the other 5:9 (800 x 1440) since my monitor is 21:9. The displays are working, but it will only let me split right down the middle. I tried to change the display resolutions in the NVIDIA Control Panel, but it just leaves empty black space and does not adjust to fit. Is there any way to customise the resolutions of PBP? If it helps I connected both display cables to the same PC since I want the displays to function as two separate monitors in Windows 11.